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Koo, Soo Kyung; Kim, Doo Yeon; Park, Sang Dai; Kang, Kae Won; Joe, Cheol O.

doi:10.1023/a:1006831114120

Cited by 26 publications

(8 citation statements)

References 49 publications

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“…Cx43 has been identified as a substrate of MAP kinase (30), protein kinase C (49), and p34 cdc2 kinase (29), and it has been shown that GJC is rapidly reduced by the increased phosphorylation of Cx43 on serine residues (11,12,29). MAP kinase constitutes one of the most important protein kinase families for the progression of the cell cycle.…”

Section: Discussionmentioning

confidence: 99%

“…Activated MAP kinase phosphorylates a variety of targets including other protein kinases and transcription factors (50). Recently it was shown that Cx43 is a substrate of MAP kinase and that the phosphorylation of Cx43 is mitosis-specific in many types of cells (11,12,29,30). Comparison of the amino acid sequences of MAP kinase substrates has identified PX 1-2(S/T)P as a consensus phosphorylation site (51)(52)(53).…”

Section: Discussionmentioning

confidence: 99%

“…A correlation exists between decreases in gap junctional communication (GJC) 1 and the cellular events that lead to cell cycle progression; for example, GJC is reduced during the G 1 to S phase transition of the cell cycle (11,12). In addition, factors that affect cell proliferation were found to inhibit GJC, including tumor promoters (15,16), growth factors (10,17), carcinogens (18,19), and oncogene products (20 -22).…”

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confidence: 99%

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Gating Connexin 43 Channels Reconstituted in Lipid Vesicles by Mitogen-activated Protein Kinase Phosphorylation

Kim¹,

Kam²,

Koo³

et al. 1999

Journal of Biological Chemistry

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103

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The regulation of gap junctional permeability by phosphorylation was examined in a model system in which connexin 43 (Cx43) gap junction hemichannels were reconstituted in lipid vesicles. Cx43 was immunoaffinity-purified from rat brain, and Cx43 channels were reconstituted into unilamellar phospholipid liposomes. The activities of the reconstituted channels were measured by monitoring liposome permeability. Liposomes containing the Cx43 protein were fractionated on the basis of permeability to sucrose using sedimentation in an iso-osmolar density gradient. The gradient allowed separation of the sucrose-permeable and -impermeable liposomes. Liposomes that were permeable to sucrose were also permeable to the communicating dye molecule lucifer yellow. Permeability, and therefore activity of the reconstituted Cx43 channels, were directly dependent on the state of Cx43 phosphorylation. The permeability of liposomes containing Cx43 channels was increased by treatment of liposomes with calf intestinal phosphatase. Moreover, liposomes formed with Cx43 that had been dephosphorylated by calf intestinal phosphatase treatment showed increased permeability to sucrose. The role of phosphorylation in the gating mechanism of Cx43 channels was supported further by the observation that phosphorylation of Cx43 by mitogenactivated protein kinase reversibly reduced the permeability of liposomes containing dephosphorylated Cx43. Our results show a direct correlation between gap junctional permeability and the phosphorylation state of Cx43.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Gating Connexin 43 Channels Reconstituted in Lipid Vesicles by Mitogen-activated Protein Kinase Phosphorylation

Kim¹,

Kam²,

Koo³

et al. 1999

Journal of Biological Chemistry

Self Cite

103

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“…In fact, connexin phosphorylation seems to be a major mechanism underlying GJIC alterations in liver cell cycling. In serum-stimulated rat liver cells, progression from the G0 state to the S phase is related to protein kinase C-dependent phosphorylation of Cx43 and disruption of GJIC (Koo et al, 1997). The relevance of altered GJIC during cell cycling is unclear.…”

Section: Function Of Liver Gap Junctionsmentioning

confidence: 99%

Structure, Regulation and Function of Gap Junctions in Liver

Willebrords

Yanguas

Maes

et al. 2015

Cell Communication & Adhesion

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Gap junctions are a specialized group of cell-to-cell junctions that mediate direct intercellular communication between cells. They arise from the interaction of 2 hemichannels of adjacent cells, which in turn are composed of 6 connexin proteins. In liver, gap junctions are predominantly found in hepatocytes and play critical roles in virtually all phases of the hepatic life cycle, including cell growth, differentiation, liver-specific functionality and cell death. Liver gap junctions are directed through a broad variety of mechanisms ranging from epigenetic control of connexin expression to posttranslational regulation of gap junction activity. This paper reviews established and novel aspects regarding the architecture, control and functional relevance of liver gap junctions.

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“…Changes in the phosphorylation status of Cxs seem to be important in the mechanism responsible to GJIC alteration during the cell cycle. Modification of the phosphorylation status of Cx43 is under the dependence of PKC activity (stages G0/S and G2/M) [21,22], and p34 cdc2 (stages G2/M) [23,24]. Cx43 transfection and functional GJIC restoration in dog kidney cells, were induced by the decrease of cyclin A, D1, D2, and cyclin dependent kinases CDK 5 and 6 when the cyclin E and CDK 2 and 4, were unaffected [16].…”

Section: Cell Cyclementioning

confidence: 99%

Connexins as Precocious Markers and Molecular Targets for Chemical and Pharmacological Agents in Carcinogenesis

Pointis

Fiorini²,

Gilleron³

et al. 2007

CMC

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Gap junctions, intercellular channels structured by the connexin protein family, have been implicated in the control of cell homeostasis, proliferation, differentiation and death. A loss of the gap junction intercellular communication and/or connexin dysfunction are typical features of cancer per se and have been associated with the effect of many carcinogens. Indeed, many early human neoplasia of various organs and human tumor cell lines exhibit deficient connexin-mediated communication expression mainly related, in a large number of observations, with an aberrant cytoplasmic localization of this membranous protein. Restoration of normal phenotype in transformed cells by restoration of exogenous connexin gave rise to the concept that connexins may act as tumor suppressors. However, the mechanisms by which connexins mediate such a tumor suppressor effect are multiple. They may result from: formation of functional channels; hemichannels or are directly associated with connexin expression. In addition, the literature shows that they may be dependent upon the cell type and the connexin type. In the present review, we analyze all these aspects of connexin/gap junction involvement in the carcinogenesis process, in human cancers and discuss the possibility of using connexins as potential anti-oncogenic targets for cancer chemoprevention and/or chemotherapy.

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Cited by 26 publications

References 49 publications

Gating Connexin 43 Channels Reconstituted in Lipid Vesicles by Mitogen-activated Protein Kinase Phosphorylation

Gating Connexin 43 Channels Reconstituted in Lipid Vesicles by Mitogen-activated Protein Kinase Phosphorylation

Structure, Regulation and Function of Gap Junctions in Liver

Connexins as Precocious Markers and Molecular Targets for Chemical and Pharmacological Agents in Carcinogenesis

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